Template for and method of installing a plurality of foundation elements in an underwater ground formation

ABSTRACT

A template for use in installing a plurality of foundation elements, in particular anchor piles, relative to one another in an underwater ground formation, comprises at least a guide for guiding a foundation element in a guiding direction during driving the foundation element into a seabed, and a frame including a holding member for holding the guide in transverse direction of the guiding direction. The template further comprises a levelling mechanism for levelling the frame with respect to a seabed when it is placed thereon. The guide is freely displaceable with respect to the holding member in the guiding direction.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Section 371 National Stage Application ofInternational Application PCT/NL2013/050076 filed Feb. 8, 2013 andpublished as WO2013/122457 A1 in English.

BACKGROUND

The discussion below is merely provided for general backgroundinformation and is not intended to be used as an aid in determining thescope of the claimed subject matter.

The present invention relates to a template for use in installing aplurality of foundation elements, in particular anchor piles, relativeto one another in an underwater ground formation, comprising at least aguide for guiding a foundation element in a guiding direction duringdriving of the foundation element into a seabed, and a frame including aholding member for holding said guide in transverse direction of theguiding direction.

Such a template is known from the European patent application EP 2 402511 of the same applicant. The known template is suitable to installanchor piles in a predetermined formation with the template remainingstationary on the seabed. The template can be re-used for installingfurther foundation elements on other sites since after installing theanchor piles the template is lifted over the ends of the installed pilesthat project upwardly from the seabed and moved to the next installationsite. The installed anchor piles may receive a jacket as a base for awind turbine, for example a tripod jacket.

SUMMARY

This Summary and the Abstract herein are provided to introduce aselection of concepts in a simplified form that are further describedbelow in the Detailed Description. This Summary and the Abstract are notintended to identify key features or essential features of the claimedsubject matter, nor are they intended to be used as an aid indetermining the scope of the claimed subject matter. The claimed subjectmatter is not limited to implementations that solve any or alldisadvantages noted in the Background

A template according to an aspect of the invention comprises a levellingmechanism for levelling the frame with respect to a seabed when it isplaced thereon, and wherein the guide is freely displaceable withrespect to the holding member in the guiding direction.

Due to this feature, the template provides the opportunity to positionthe guides vertically without loosing contact with the seabed. Since theguide is freely displaceable with respect to the holding member, theframe may force the guide to a desired vertical position upon levellingthe frame on an inclined seabed, for example. In such a case it is notnecessary to apply additional power tools to move the guide with respectto the holding member.

The guide may be provided with a suspended element, wherein the guideand the holding member are adapted such that upon lifting the frame theholding member displaces upwardly with respect to the guide until theholding member contacts the suspended element of the guide so as to liftthe guide, as well. In this embodiment the suspended element may havethe function of a temporarily locking means, for example in case oftransporting the template from a vessel to the seabed, since the guidemay suspend from the holding member by means of the suspended elementupon supporting the frame. Instead of or in addition to the suspendedelement the template may comprise an alternative locking device forlocking the guide with respect to the holding member in a predeterminedmutual position. In a practical embodiment the suspended elementcomprises an arresting ring and the holding member has a cylindricalupper end surrounding the guide, wherein the arresting ring has a largerdiameter than the upper end of the holding member.

The guide may comprise a sleeve for surrounding a foundation elementduring driving. Preferably, the guide comprises a sound insulatingsleeve, because this reduces underwater noise input during driving afoundation element into the seabed.

The levelling mechanism may comprise at least an inflatable bag mountedat a bottom portion of the frame. The bag may be inflated by means of afluid, i.e. a liquid or a gas. Under off-shore conditions inflating byusing sea water may be preferred. The bag is preferably provided with anouter shield for protecting the bag. The levelling mechanism may belocated at a distance from the holding member and the guide.

In a practical embodiment the holding member comprises two aligned ringslocated at a distance from each other, which rings surround the guide.In this case the center lines of the rings substantially coincide. Theguide may extend above the holding member, but in general the smallestportion of its length will extend above the holding member, for exampleless than 25% of its length.

In an alternative embodiment the frame comprises at least two firstrings at angular distance around a central axis of the frame and arotation device for rotating a second ring between the angular positionsof the first rings such that a temporary holding member for holding asleeve-shaped guide can be formed at each of the respective angularpositions. This means that a first temporary holding member includingone of the first rings and the second ring, and a second temporaryholding member including the other one of the first rings and the secondring can be formed. In this embodiment it is possible that the guide isremoved from the first temporary holding member after guiding thefoundation element during driving this into the seabed before formingthe second holding member.

The invention is also related to a method of installing a plurality offoundation elements by means of a template as described hereinbefore,wherein the frame including the guide is placed on a seabed, after whichthe frame is levelled by means of the levelling mechanism. The levellingaction will move the frame with respect to the seabed to a position inwhich the holding member holds the guide in a vertical position. Sincethe guide is freely displaceable with respect to the holding member theguide can automatically arrive in the desired vertical position duringthe levelling action.

After installing the foundation elements by inserting the foundationelements into the corresponding guides and driving them into the seabed,the template including the guide may be lifted over the ends of theinstalled foundation elements extending above the ground formation, andmoved to another site for installing a plurality of foundation elements.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the invention will hereafter be elucidated with reference todrawings showing an embodiment of the invention very schematically.

FIG. 1 is a perspective view of an embodiment of a template.

FIG. 2 is a similar view as FIG. 1 as seen from above, partially in acut-away view.

FIG. 3 is a similar view as FIG. 1, but showing an alternativeembodiment of a template.

FIG. 4 is a similar view as FIG. 3 as seen from above, partially in acut-away view.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS

FIGS. 1 and 2 show an embodiment of a template 1. The template 1comprises a frame 2 which has four holding members 3 for holdingrespective guides 4. Each of the holding members 3 comprises a lowerring and an upper ring for holding the guide 4. The guide 4 serves toguide a foundation element such as an anchor pile A during driving, seeFIG. 2. In the embodiment as shown in FIGS. 1 and 2 the template 1comprises four guides 4 which are formed by hollow cylinders or sleevesthat surround the anchor pile A during driving. Each of the guides 4 hasa guiding direction which extends along the center line of the cylinder.In practice the guiding direction is substantially vertical since it ismostly desired to install anchor piles A vertically.

The holding members 3 of the template 1 are fixed relative to each otherby means of the frame 2 such that a plurality of anchor piles A can bedriven into a seabed 5 in a predetermined pattern. The center lines ofthe guides 4 of the embodiment as shown correspond to a square as seenfrom above, but different shapes and dimensions are conceivable,dependent on the structure of a jacket that must be placed onto theinstalled anchor piles A afterwards.

After installing the template 1 from a surface vessel (not shown) ontothe seabed 5, the anchor piles A are transported to the template andinserted into the guides 4. Each of the anchor piles A is driven intothe seabed 5 by means of a hydraulic driver 6, for example an IHCHydrohammer, which is connected to a power pack on board of the surfacevessel. FIG. 1 shows four drivers 6, but it is conceivable to use lessdrivers 6 such that one driver 6 drives more than one anchor pile A intothe seabed 5. In the embodiment as shown in FIGS. 1 and 2 each of theguides 4 is provided with a sound-insulating sleeve that surrounds theanchor pile A during driving. This reduces noise input from the driver 6into the surrounding water. Such a sound-insulating sleeve may be of thetype as described in EP 2 402 511. It is noted that in case of noisereduction sleeves the length of the guides 4 have at least the samelength as the anchor piles A, which may be 30-50 m, for example.

FIG. 1 illustrates a situation in which the guides 4 project above thewater surface when the template 1 rests on the seabed 5, but in analternative embodiment the lengths of each of the guides 4 may be suchthat they stay below sea level.

Furthermore, the template 1 is provided with a levelling mechanism forlevelling the frame 2 with respect to the seabed 5 in order to be ableto create vertical positions of the guides 4. The levelling mechanism inthe embodiment as shown in FIGS. 1 and 2 comprises four inflatable bags7. The bags 7 are disposed at a mutual distance and mounted to a bottomportion of the frame 2. The bags 7 can be inflated independently fromeach other so as to level the frame 2 with respect to the seabed 5, forexample when the seabed is inclined at the location where the template 1is placed.

The guides 4 are freely displaceable with respect to their correspondingholding members 3 in the guiding direction. In the embodiment as shownin FIGS. 1 and 2 the guides 4 can slide within their corresponding ringsof the respective holding members 3. When placing the template 1 ontothe seabed 5 the guides 4 may also rest on the seabed 5. If the frame 2is levelled by means of the bags 7 the holding members 3 will belevelled accordingly. Since the guides 4 are freely displaceable withrespect to the respective holding members 3 the guides 4 can beautomatically positioned vertically whereas the guides 4 remain on theseabed 5. This may be desired for minimizing sound emission duringdriving of the anchor piles A into the seabed 5.

FIGS. 1 and 2 show that each of the guides 4 is provided with asuspended element, in this case an arresting ring 8. The arresting ring8 is attached to the guide 4 and has a larger outer diameter than theinner diameter of the upper ring of the corresponding holding member 3.As a consequence, upon lifting the frame 2, for example from the seabed5 after the anchor piles A have been driven into the seabed 5, theholding members 3 are displaced upwardly with respect to the guides 4until the upper rings of the holding members 3 support the respectiveguides 4 at the arresting rings 8. On the other hand, upon placing theframe 2 including the guides 4 onto the seabed 5 at a different site theguides 4 will contact the seabed 5 prior to the frame 2 contacts theseabed such that the holding members 3 are subsequently displaceddownwardly with respect to the respective guides 4 until the frame 2also contacts the seabed 5. During the latter action the contact betweenthe arresting rings 8 and the corresponding holding members 3 will belost. This condition can be achieved in case the length of the guide 4below the arresting ring 8 is larger than the distance between an uppercontact surface of the upper ring of the holding member 3 with thearresting ring 8 and the bottom of the frame 2 which contacts the seabed5.

In a next step, the frame 2 can be levelled by means of inflating thebags 7 such that the arresting rings 8 may remain free from contact withthe corresponding holding members 3. Hence, during levelling the guides4 are freely displaceable with respect to the corresponding holdingmembers 3. In this case the arresting rings 8 are used to transport theguides 4 together with the frame 2. In fact they form a locking devicefor locking the guide 4 with respect to the holding member temporarily.

Alternatively, the length of the guide 4 below the arresting ring 8 maybe shorter than the distance between an upper contact surface of theupper ring of the holding member 3 with the arresting ring 8 and thebottom of the bags 7 in at least an inflated condition thereof. Thismeans that in the inflated condition the guides 4 may be free from theseabed 5 such that upon levelling the frame 2 the guides 4 willautomatically obtain a vertical position when they suspend from therespective upper rings of the holding members 3. If the guides 4 loosetheir contact with the seabed 5 upon inflating the bags 7 a horizontalforce on the guides 4 by the seabed 5 will be eliminated in case oflevelling the frame 2 at an inclined seabed 5.

The embodiment of the template 1 as shown in FIGS. 1 and 2 comprisesfour holding members 3 at equi-angular positions around a central axisof the frame 2, but a different number of holding members 3 isconceivable.

Furthermore, the template 1 is provided with coupling members 9 forcoupling the rings of the holding members 3 to the rest of the frame 2.The coupling members 9 may be provided with easy fittings in order to beable to replace the rings quickly, for example by rings of a differentsize, or to introduce an additional rod between the rings and the restof the frame 2 so as to increase the distances between the central axisof the frame 2 and the holding members 3. It is also possible that thecoupling members 9 comprise a spring and/or damping function in order toreduce transfer of vibrations from the drivers 6 to the frame 2.

FIGS. 3 and 4 show an alternative embodiment of the template 1 accordingto the invention. In these figures identical reference signs as used inFIGS. 1 and 2 are now used for corresponding parts. In the embodiment ofFIGS. 3 and 4 the frame 2 comprises three first rings 3A, which arelocated at equi-angular distance around the central axis of the frame 2.The frame 2 is further provided with a rotation device 10, in this casea horizontal bar which is rotatable about the central axis of the frame2. At the end of the bar a second ring 3B is mounted. The rotationdevice 10 can rotate the second ring 3B between the angular positions ofthe first rings 3A. In this case the second ring 3B is substantially thesame as the first ring 3A, but may be different in an alternativeembodiment.

FIG. 4 shows a condition in which the second ring 3B is turned above thefirst ring 3A at the left side of the template 1 such that both rings3A, 3B are aligned in upward direction and have coinciding central axes.Thus, at that side of the template 1 a temporary holding member 3A, 3Bis formed for holding the guide 4. In this condition an anchor pile Acan be inserted in the temporary holding member 3A, 3B. After drivingthe anchor pile A into the sea bed, and possibly removing the guide 4from the temporary holding member 3A, 3B, the rotating device 10 can berotated such that the second ring 3B is located above and aligned withanother first ring 3A so as to form a next temporary holding member 3A,3B, in which the guide 4 can be placed.

In fact, the template 1 as shown in FIGS. 3 and 4 only needs one driver6 and one guide 4. After installing the anchor piles A, the template 1is lifted over the ends of the installed foundation elements extendingabove the ground formation, and moved to another site where other anchorpiles A can be installed.

The template 1 as shown in FIGS. 3 and 4 can form three temporaryholding members 3A, 3B, but templates for creating more or lesstemporary holding members are possible.

From the foregoing it will be clear that the template according to theinvention provides a simple template which can be easily leveled on anon-flat seabed.

The invention is not limited to the embodiment shown in the drawings anddescribed hereinbefore, which may be varied in different manners withinthe scope of the claims. For example, it is possible that the holdingmember comprises a single cylindrical element instead of two alignedrings. The levelling device may comprise alternative lifting means suchas hydraulic cylinders or the like.

What is claimed is:
 1. A template for use in installing a plurality offoundation elements, in particular anchor piles, relative to one anotherin an underwater ground formation, comprising: at least a guideconfigured to guide a foundation element in a guiding direction duringdriving the foundation element into a seabed; a frame including aholding member configured to hold said guide in a transverse directionof the guiding direction, wherein the guide is freely displaceable withrespect to the holding member in the guiding direction; and a levellingmechanism configured to level the frame with respect to a seabed whenthe frame is placed thereon.
 2. The template according to claim 1,wherein the guide is provided with a suspended element, and wherein theguide and the holding member are configured such that upon lifting theframe the holding member displaces upwardly with respect to the guideuntil the holding member contacts the suspended element of the guide soas to lift the guide, as well.
 3. The template according to claim 1,wherein the guide comprises a sleeve configured to surround a foundationelement during driving.
 4. The template according to claim 2, whereinthe suspended element comprises an arresting ring and the holding memberhas a cylindrical upper end surrounding the guide, wherein the arrestingring has a larger diameter than the upper end of the holding member. 5.The template according to claim 1, wherein the guide comprises a soundinsulating sleeve.
 6. The template according to claim 1, wherein thelevelling mechanism comprises at least an inflatable bag mounted at abottom portion of the frame.
 7. The template according to claim 6,wherein the inflatable bag is provided with an outer shield forprotecting the bag.
 8. The template according to claim 1, wherein thetemplate comprises a locking device configured to lock the guide withrespect to the holding member.
 9. The template according to claim 1,wherein the holding member comprises two aligned rings located at adistance from each other, which rings surround the guide.
 10. Thetemplate according to claim 1, wherein the template comprises three orfour holding members including corresponding guides at equi-angularpositions around a central axis of the frame.
 11. The template accordingto claim 1, wherein the frame comprises at least two first rings atangular distance around a central axis of the frame -and a rotationdevice configured to rotate a second ring between the angular positionsof the first rings such that a temporary holding member configured tohold a sleeve-shaped guide is formed at each of said respective angularpositions, hence a first temporary holding member including one of saidfirst rings and the second ring, and a second temporary holding memberincluding the other one of said first rings and the second ring.
 12. Amethod of installing a plurality of foundation elements, in particularanchor piles, relative to one another in an underwater ground formationwith a template including at lease a guide configured to guide afoundation element in a guiding direction during driving the foundationelement into a seabed, and a frame including a holding member configuredto hold said guide in transverse direction of the guiding direction,wherein the frame including the guide is placed on a seabed, after whichthe frame is levelled by a levelling mechanism.
 13. The method accordingto claim 12, wherein, after installing the foundation elements, thetemplate including the guide is lifted over the ends of the installedfoundation elements extending above the ground formation, and moved toanother site for installing a plurality of foundation elements.